Brake shoe



y 1940- c. F. HIRSHFELD 2,207,151

BRAKE SHOE Filed Aug. 11, 19s? CLn/Zfx/c 5 P $62.90 P47 (3 IN VENTOR.

ATTORNEY.

Patented July 9, 1940 UNITED STATES PATENT. OFFICE BRAKE SHOE Application August 11, 1937, Serial No. 158,589

3 Claims.

This invention relates to track brake shoes of the type which are generally suspended between tandem wheels of a rail vehicle and which are maintained in frictional engagement with tracks 5 by magnetic lines of forces in response to the energization of an electrical circuit by the vehicle operator.

It is customary to construct these brake shoes in the form of a casing or body portion in which 1 a coil in the electrical circuit is housed, the coil being wound around a metallic core with the ends of the core being positioned downwardly thus forming an electro-magnet. Wear plates of some wear resistant magnetic material are bolted or otherwise rigidly secured to the legs of the electro-magnet, these plates being strips having a length substantially coextensive with the length of the casing and residing materially parallel in a direction parallel to the rail with which they are adapted to contact. The rails are workhardened at their top surfaces by wheels passing thereover. However, the pressure between the rails and these wear plates is so great that both the wear plates and the rails wear rapidly, the

wear on the rails being in destruction of the workhardened surface in parallel paths, leaving a land or ridge therebetween. The top of the land, being untouched by the wear plates remains hardened and the wheels subsequently. passing thereover are largely supported by this land which tends to groove the wheels and which likewise prevents work hardening action of the wheels on the remainder of the head of the rail so that when the wear plates again contact the rail at this region the wear is at an increased rate.

The principal object of this invention is to provide a track shoe of such construction that the wear on the rails will be uniform across the rail to accomplish the triple purpose of preserving the work-hardened surface of the rail because of the increased area of the wear surfaces, eliminating the formation of a ridge on the rail,

whereby subsequent passage of wheels thereover will continue -to harden the entire surface and eliminating the localized wear of the wheel tires as a result of eliminating the rail ridges.

More specifically it is an object of this invention to provide a third wear plate for residence between the above mentioned wear plates whereby there is no visible spacing between the wear plates, the third plate being of a non-magnetic material such as stainless steel, in order to preserve the magnetic spacing therebetween, and having abrasive and abrasive resistant qualities similar to those of the shoe whereby it wears equally with the other plates and also wears the rail in a similar manner thereto.

Another object is to so shape this third plate as to length and end formation that it will serve to preclude the entry of snow and other extraneous 5 matter between the magnetic wear plates.

Other objects and advantages will hereinafter become more apparent as reference is bad to the accompanying drawing wherein:

Fig. 1 is a side elevation of a track brake shoe 10 with my invention incorporated therein, and

Fig. 2 is a transverse vertical section taken along the line 2--2 of Fig. 1.

More particularly, a central core or bar i of metal having high magnetic permeability has a 15 length somewhat less than the overall length of the shoe, and around which are numerous turns 2 of wire having high electrical conductivity. The core I may be considered as the base of a U- shaped electro-magnet, the side plates 9 forming 20 the branches of the U and being secured to the base or core I by means of heavy bolts 4 and nuts 5. This constitutes a single source of excitation for the side members 3 and pole pieces or wear plates 8. Secured to the lower edges of the 25 side plates 3 by bolts 6 and nuts I are wear plates 8. -The plates 8 are laterally spaced from each other and extend in parallel relation, defining the over-all length of the brake shoe.

As previously discussed, these wear plates do 30 not wear a rail uniformly because of the gap therebetween. I, therefore, interpose between these plates a further wear plate 9 made of a material of very low magnetic permeability, such as stainless steel, this plate being, preferably, of 35 a length equal to that of the side plates and also having about the same abrasive and abrasive resistant qualities as the wear plates in order to wear uniformly therewith and in order to similarly affect the contacted rails. The ends of the 0 plate 9 are turned upwardly as indicated at 10 to constitute means for precluding the entry of snow and other extraneous matter into the ends of the shoe. The plate 9 is thus shaped like an elongated U with the legs extending upwardly so that the upper surfaces thereof are substantially coplanar with the upper surfaces of the side plate 3. As will be apparent from Fig. 1, the leading and trailing edges of the plate 9 are beveled to enable the plate 9 to ride over irreguw larities in the track when in contact therewith.

The coil 2 is adapted for connection to a controlled source of electrical energy through a cable l2. Energization of the coil magnetizes the plates 3 and, hence, the plates 8 whereby the 55 shoe is drawn against the rails with a force proportionate to the intensity of the current flow and resultant magnetism.

The shoe is equipped with brackets II, which may be suitably connected thereto by the bolts l, and which may be connected to supporting springs (not shown) so that the induced magnetism may also be employed to cause lowering of the shoe to the rails, as is understood in the art.

The stainless steel above referred to may be of any found suitable among the many types now on the market, such as, for example, that commonly known as l88 and composed of Per cent Chromium 18.00 to 19.00 Nickel 7.00 to 9.00 Carbon -a 0.68 to 0.20 Silica 0.75 maximum Manganese 0.60 maximum This invention may be developed within the scope of the following claims without departing from the essential features of said invention and it is desired that the specification and drawing be read as being merely illustrative of one form bridging the gap between said members at the rail contacting surfaces thereof, said wear plate having a beveled leading edge and a portion extending upwardly therefrom to exclude extraneous matter from between said wear plates.

2. A track brake shoe comprising parallel. spaced, rail contacting members made of magnetic material with the long surfaces thereof paralleling the rail with whichthe shoe contacts, upwardly extending magnetic plates for supporting said members, means for rendering said mem- '-bers magnetic, anda U-shaped wear plate of nonmagnetic material bridging the gap between said members at the rail contacting surfaces thereof and having an upturned front end as a guard against the entry of extraneous matter into the shoe thereabove, the upper surface of said upturned end being substantially coplanar with the upper surfaces of said magnetic plates.

3. A track brake shoe comprising a core, a coil of wiring around said core, parallel, spaced, rail contacting members made of magnetic material with the long surfaces thereof paralleling the rail with which the shoe contacts and residing on each side of said wiring, means for energizing said coil thereby rendering said members magnetic, and a wear plate of non-magnetic material between said members rigidly secured thereto in such manner that the bottom of the shoe appears as an uninterrupted surface, said wear plate extending to the front end of said shoe and having an up-turned front end as a guard against the entry of extraneous matter into the shoe thereabove.

CLARENCE F. HIRSHFELD. 

